Cpu scheduler, computer science, Basic Computer Science

Selects among the processes in memory which are ready to execute & allocates the CPU to one of themCPU scheduling decisions can be taken place when a process:A. TerminatesB. Switches from running to waiting stateC. Switches from running to ready stateD. Switches from waiting to readyScheduling under 1 & 4 is nonpreemptiveAll other scheduling is preemptive